Arc lamp or the like



Aug. 3, 1948. c. G. H. HALLETT ARC LAMPS OR THE LIKE Filed Oct. 28, 1947Patented Aug. 3, 1948 ARC LAMP OR THE LIKE Charles Gordon Heys Hallett,London, England, assignor to Morgan Crucible Company Limited, London,England, a company of Great Britain Application October 28, 1947, SerialNo. 782,595 In Great Britain March 29, 1947 11 Claims. 1

This invention relates to improvements in the contacts which carry thecurrent into the electrodes in arc lamps, electric welding machines andthe like.

It provides an improvement in or development of the invention containedin our co-pending application, Patent No. 2,442,409, filed June 3, 1946for Improvements in and relating to are lamps or the like according towhich the contact blocks each comprise a series of wedge elements, onebehind the other, coacting with a corresponding series of slopingsurfaces formed in the electrode holder so that a thrust parallel to theelectrode, i. e. a longitudinal thrust, causes the contact block to bearwith pressure upon the electrode holder and upon the electrode. Moreparticularly the wedge elements of the contact block substantiallyproduce a helical formation matching a helical thread in the electrodeholder. With this latter arrangement there is a, tendency in cases wherethe electrode is fed with a rotary movement, for the contact blockassembly to become unscrewed, and the object of the present invention isto counteract such tendency.

The present invention accordingly provides a device in the nose-piece ofthe electrode holder whereby the contact blocks are prevented fromrotation with the electrode and which ensures that, although the contactblocks are prevented from such movement, they will be free to move,under spring pressure or other yielding longitudinal thrust,sufficiently to produce the required wedge action.

The invention is illustrated in the accompanying drawings in which Fig.l is a part sectional elevation of a nose-piece of an electrode holder,Fig. 2 is a section on the line 22. Fig. 1 and Figs. 3 and 4 aresectional elevations of modified forms of apparatus.

Referring to the drawings the nose-piece indicated generally at I of theelectrode holder 2 is provided with an opening at the front 3 for theinsertion of the contact blocks 4 which are adapted to be screwed homeby means of a suitable tool, and within the electrode holder isrotatably accommodated a member 5 adapted to interlock with the contactblocks 4 so as to be rotated there with during the last part of thescrewing operation, the said member 5 being provided with one or morelongitudinal slots 5 for receiving a looking pin or detent I which canbe brought into and out of operation at will.

The rear ends of the contact blocks 4 are formed with a series of dogs 8which engage, when the contact blocks have been screwed some distance(Cl. l76119) into the electrode holder 2, with a corresponding series ofdogs 9 on the interlocking member '5 so as to produce a-dog-clutch. Thedogs 8,9 are so shaped as to permit free movement of the contact blocks4 in a radial direction. The interlocking member 5 conveniently takesthe form of a sleeve annularly disposed around the electrode it, whichsleeve is formed internally, e. grwitha flange II, so as to provide aseating for a .com-. pression spring I2 transmitting longitudinalthrustto the contact blocks 4.

The locking pin I is preferably housed within a centrally bored bush I3which is screwed into, the side wall I4 of the electrode holder 2, haveing a cylindrical recess I5 in its inner end to ace commodate a smallcompression spring I6 mounte ed under a collar I1 on the pin I so asnormally to urge the pin into a retracted position. The outer end of thepin I carries a knob I8 easily ac-v cessible to the operator of the arclamp and adapted when depressed to. be locked in that position, forexample by means of a bayonet fastening I9.

In operation the contact blocks 4 are screwed into the electrode holder2 by means of a suitable tool until the dogs 8 located on their rear.ends engage the corresponding dogs 9 locatedon the end of the sleeve 5.Thereupon the sleeve 5 rotates with the contact blocks 4, the lockingpin i being in the retracted position, and is forced back with thecontact blocks 4 against the action of the compression spring I2 whoseend is housed in the sleeve. When the contact blocks 4 have been screwedfully home or substantially so, a longitudinal slot 6 in the sleeve 5being in register beneath the retracted locking pin I, the pin isdepressed into the slot 6 by its external knob I8 and the latter isturned so as to lock the pin. The sleeve 5 and the associated contactblocks 4 are then looked against rotation.

In the modification shown in Fig. 3 the locking pin I is engaged at itsouter end by a leaf spring at mounted on the outside of the electrodeholder 2, one end of the spring being anchored to the holder at 2| andthe other terminating in an out wardly curved portion 22 which serves asa finger grip. By grasping the finger grip 22, the spring 20 may belifted to retract the locking pin I and disengage it from the sleeve 5.When the spring 29 is released the locking pin I will be depressed.

In a further modification shown in Fig. 4 the locking pin I is formedwith a collar 23 engaged on its underside by a trip lever 24 actuated bya pivoted saddle 25 so that when the latter is depressed the locking pinI will be retracted against the action of a spring 26.

What I claim is:

1. The combination of an electrode, an electrode holder, and a pluralityof complementary contact blocks surrounding the electrode and interposedbetween the electrode and the electrode holder, each contact blockhaving a series of surfaces sloping towards the electrode which in theassembly of contact blocks produce a helical formation and the electrodeholder having a helical thread matching said helical formation, andmeans for locking the contact blocks against rotation in the electrodeholder.

2. The combination as claimed in claim 1 wherein the locking meansincludes a member rotatably accommodated within the electrode holder,said member being adapted to interlock with the contact blocks so as tobe rotated therewith during the last part of the screwing operation whenthe contact blocks are screwed home, and means operable to lock saidmember against rotation.

3. The combination as claimed in claim 1 wherein the locking meansincludes a member rotatably accommodated within the electrode holder,dogs formed on said member adapted to interlock with the contact blocksso that said member is rotated therewith during the last part of thescrewing operation when the contact blocks are screwed'home, and meansoperable to lock said member against rotation.

4. The combination as claimed in claim 1 including a locking member inthe form of a sleeve annularly disposed around the electrode, acompression spring for transmitting longitudinal thrustupon the contactblocks, said sleeve being formed internally with a flange so as toprovide a seating for said compression spring and being formed with atleast one longitudinal slot, and a locking device engageable with saidslot.

5. The combination as claimed in claim 1 including a locking memberformed with at least one longitudinal slot, a locking pin, engageablewith said slot, a centrally bored bush screwed with the electrode holderand accommodating said pin, and a compression spring mounted in saidbush to urge the pin out of engagement with said slot.

6. The combination as claimed in claim 1 including a locking memberformed with at least one longitudinal slot, a locking pin engageablewith said slot, a centrally bored bush screwed into the electrodehold-er and accommodating said pin, a compression spring mounted in saidbush to urge the pin out of engagement with said slot, and a projectioncarried by the pin for engagement with a recess formed in the bush tolock the pin in engagement with said slot.

7. The combination as claimed in claim 1 including a locking memberformed with at least one longitudinal slot, a locking pin engageablewith said slot, a leaf spring mounted on the outside of the electrodeholder and bearing on said pin, one end of said spring being anchored tothe holder and the other terminating in a curved portion serving as a,finger grip.

8. The combination as claimed in claim 1 including a, locking memberformed with at least one longitudinal slot, a locking pin engageablewith said slot, a collar formed on said pin, a trip lever engaging theunderside of said collar, and a pivoted saddle which when depressedactuates the trip lever to withdraw the pin from engagement with saidslot.

9. The combination of an electrode, an electrode holder, and a pluralityof complementary contact blocks surrounding the electrode and interposedbetween the electrode and the electrode holder, each contact blockhaving a series of surfaces sloping towards the electrode which in theassembly of contact blocks produce a helical formation and the electrodeholder having a helical thread matching said helical formation, andmeans for locking the contact blocks against rotation in the electrodeholder, said electrode holder comprising a nose piece provided with anopening for the insertion and screwing home of the contact blocks.

10. The combination as claimed in claim 9 wherein the locking meansincludes a member rotatably accommodated within the nose piece of theelectrode holder, dogs formed on said member, correspondingly formeddogs on the contact blocks adapted to interlock with the dogs formed onsaid member, so that said member is rotated therewith during the lastpart of the screwing operation when the contact blocks are screwed home,and means operable to lock said member against rotation.

11. The combination as claimed in claim 9 wherein the locking meansincludes =a, member rotatably accommodated within the nose-piece of theelectrode holder, dogs formed on said member,

correspondingly formed dogs on the contact blocks adapted to interlockwith the dogs formed on said member, the correspondingly formed dogsbeing so shaped as to permit relative movement of the contact blocks ina radial direction, and means operable at will to lock said memberagainst rotation.

CHARLES GORDON HEYS HALLETT.

